Capacitor discharge type contactless ignition system for internal combustion engines

ABSTRACT

The ignition system is provided at least two coils for generating voltages with phase different from each other. One of the coils charges a capacitor and the other mainly generates an electric signal for preventing reverse rotation. During the reverse rotation of the engine, said other coil so operates as to let the capacitor charging current flow not to the capacitor but to the ground, thereby preventing ignition sparks.

United States Patent 11 1 [111 3,911,889

Nagasawa 1 Oct. 14, 1975 [54] CAPACITOR DISCHARGE TYPE 3,518,978 7/ 1970 Schmiedel 123/148 MC CONTACTLESS IGNITION SYSTEM FOR 3,566,188 2/1971 Minks 123/148 MC 3,598,098 8 971 Sohner et a1. 123/148 MC INTERNAL COMBUSTION ENGINES 3,723,809 3/1973 Fujii 123/148 MC Inventor: Masao Nagasawa, Kariya, Japan Nippondenso Co., Ltd., Kariya, Japan Filed: Mar. 18, 1974 Appl. No.: 452,360

Assignee:

Foreign Application Priority Data May 8, 1973 Japan 48-54205[U] Mar. 29, 1973 Japan 48-38583[U] US. Cl 123/148 R; 123/148 MC Int. Cl. F02P 3/06 Field of Search 123/148 MC References Cited UNITED STATES PATENTS 1/1970 Farr 123/148 MC Primary Examiner charles J. Myhre Assistant ExaminerJoseph Cangelosi Attorney, Agent, or FirmCushman, Darby & Cushman ABSTRACT The ignition system is provided at least two coils for generating voltages with phase different from each other. One of the coils charges a capacitor and the other mainly generates an electric signal for preventing reverse rotation. During the reverse rotation of the engine, said other coil so operates as to let the capacitor charging current flow not to the capacitor but to the ground, thereby preventing ignition sparks.

6 Claims, 29 Drawing Figures US. Patent Oct. 14, 1975 Sheet 1 of 17 3 91].,889

US. Patent Oct.14, 1975 Sheet20f17 3,911,889

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ONE REVOLUTION g PER\OD T5 T5 l REVE RSE Tl T2 T3 T4 FORWARD US. Patent 0a. 14, 1975 Sheet 3 of 17 3,911,889

US Patent Oct. 14, 1975 Sheet40f17 3,911,889

FORWARD e REVERSE US. Patent Oct. 14,1975 Sheet 5 of 17 $911,889

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US. Patent Oct.14,1975 Sheet6of 17 3,911,889

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ONE REVOLUTION PERIOD US. Patent Oct.14,1975 Sheet70f 17 3,911,889

US. Patent Oct. 14,1975 Sheet90f17 3,911,889

Fig/3 U.S. Patent Oct. 14, 1975 Sheet 10 of 17 3,911,889

US. Patent Oct. 14, 1975 Sheet110f17 3,911,889

U.S. Patent Oct. 14, 1975 Sheet 12 of 17 3 911 89 Fig.1?

Sheet 13 of 17 3,911,889

U.S. Patent OCL 14, 1975 Patent -14,1975 Sheet 15 0f17 FigoZl' Figii FORWARD REVERSE U..S. Patent Oct. 14, 1975 Sheet 16 0f 17 3,911,889

US. Patent Oct. 14, 1975 Sheet 17 of 17 3,911,889

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Top Deadcenter \Reverse Rotation Intake ort open Exhaustport open H Bottom Dedicenter CAPACITOR DISCHARGE TYPE CONTACTLESS IGNITION SYSTEM FOR INTERNAL COMBUSTION ENGINES BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates in general to a capacitor discharge type ignition system for internal combustion engines in which a magneto generator is employed as an electric power source for charging a capacitor, and especially to the system for preventing the engines from rotating in the reverse direction.

2. Description of Prior Art In a conventional ignition system of this kind, a single magnetic pole is formed at a spherical portion of a rotor. Since the generator has a small space to provide a magnet it can not produce a sufficient energy to produce ignition sparks at spark plugs. And further when the magneto generator is provided with a lamp load generating coil, it can not produce a sufficient energy on the lamp load coil, either.

SUMMARY OF THE INVENTION It is, therefore, a primary object of the present invention to provide a capacitor discharge type ignition system employing the conventional magneto generator which has a plurality of magnets spaced apart at equal intervals.

It is another object of the present invention to provide the ignition systems which prevent the engine from rotating in a reverse direction.

It is a further object of the present invention to provide the ignition system in which the capacitor is prevented from being charged during the reverse rotation of the engine, thereby to prevent the engine from rotating in the reverse direction.

It is a still further object of the present invention to provide the ignition system employing the magneto generator having a plurality of magnets spaced apart at equal intervals, in which at least two generating coils are provided on the stator for charging the capacitor, each phase of the generating voltages of which is different from each other to be detected to prevent the engine from rotating in the reverse direction.

It is a still further object of the present invention to provide the ignition system in which a transformer is connected to the generating coil for producing an ignition timing signal, thereby eliminating the timing signal generator.

It is a still further object of the present invention to provide the ignition system in which another thyristor besides the thyristor for ignition sparks is provided between both terminals of the generating coil for invalidating the generating voltages of the generating coil during the reverse rotation of the engine.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1, 4, 5, 7, 8, 10, ll, 13, 17, 19, 21 and 24 are respectively electric wiring diagrams of first to twelth embodiments of the present invention;

FIG. 2 shows a partially transverse sectional view of an internal rotor type magneto generator employed in the first embodiments of the present invention;

FIGS. 3, 6, 9, 12 and 20 are wavefrom diagrams for explaining the operation of the embodiments;

FIG. 14 is transverse sectional view of an external revolving type magneto generator employed in the seventh and eighth embodiments of the present invention;

FIG. 15 shows another external revolving type magneto generator, in which FIG. l5-A is a perspective view of the stator of the magneto generator'and FIG. 15-B is a rough plan view thereof;

FIG. 16 shows an external revolving type magneto generator employed in the third and fourth embodiments of the present invention, in which FIG. l6-A is a plan view of the stator of the magneto generator and FIG. 16-8 is an elevational view thereof;

FIG. 18 shows an external revolving type magneto generator employed in the ninth embodiment of the present invention, in which FIG. 18-A is a longitudinal sectional view taken along the line XVIIIA-XVIIIA in FIG. l8-B and FIG. l8-B is a transverse sectional view taken along the line XVIIIB-XVIIIB in FIG. 18-A;

FIG. 22 shows another external revolving type magneto generator employed in the ninth embodiment of the present invention, in which FIG. 22-A is transverse sectional view taken along the line XXIIA-XXIIA in FIG. 22-B and FIG. 22-B is a longitudinal sectional view taken along the line XXIIB-XXIIB in FIG. 22-A;

FIG. 23 is waveform diagram of the ninth embodiment employing the magneto generator shown in FIG. 22; and v FIG. 25 shows an ignition cycle of the twelth embodiment shown in FIG. 24.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Now referring to FIG. 1 showing the first embodiment of the present invention, numerals 1 and 2 designate first and second capacitor charging coils. Said first coil lwhich is mainly used at low speed rotation has a larger number of turns than that of said second coil 2 which is mainly used at high speed rotation. Numerals 3 and 4 designate battery charging coils, and 5a, 5b and 5c generating coils for other electric loads. A numeral 6 designates a pole core wound with said first coil 1, 7 a pole core for said second coil 2 and said battery charging coil 3. Numerals 8, 9 and 10 designate pole cores for said generating coil 5a, 5b and 5c, respectively and 11 a pole core for said battery charging coil 4. Those elements mentioned above constitute as a whole a magneto generator G. Said first coil 1 has a center tap 1c and comprises two winding parts la and lb. A numeral 12 designates a diode, 13 a capacitor, 14 a diode, l5 and ignition coil having a primary winding 15a and a secondary winding 15b, 16 spark plugs mounted on each cylinder of a two-cylinder-two-cycle engine, 17 a thyristor consituting a semiconductor switching element, 18 and 19 diodes, 20 a transfonner having a primary winding 20a and a secondary winding 20b for controlling said thyristor 17, 21, 22, 23 and 24 diodes respectively, 25 a battery installed in a vehicle,

26 a full-wave rectifier, 27a and 27b switch means for connecting an output terminal of said rectifier and lamp loads 28.

The construction of the above-mentioned magneto generator of a four-pole type will be described with references in FIG. 2, in which a numeral 29 designates a stator comprising six pole cores 6, 7, 8, 9, l and 11 extending internally at equal intervals, and coils 1 to c are wound thereon as previously mentioned. A numeral 30 designates a rotor comprising a permanent magnet 32 circumferentially polarized to have north and south poles 32a to 32d alternatively, four magnetic pole pieces 33a to 33d provided at the peripheral ends of said magnet 32 and a nonmagnetic material 31a such as aluminum or synthetic resin for embedding securely said magnet and magnetic pole pieces. Said rotor 30 is connected to a crankshaft 34a of an engine.

With the magneto generator constructed as above described, for each revolution of the magneto generator, i.e., for each revolution of the engine crankshaft 34a, the capacitor charging coil 1 generates two cycles of the AC voltage as shown in FIG. 3(a), while the capacitor charging coil 2 generates two cycles of the AC voltages as shown in FIG. 3(b), which is retarded with respect to that of the coil 1 by an angle of about 60. And for each revolution of the crankshaft 34a, the battery charging coil 3 generates two cycles of the AC voltages indicated by a solid line in FIG. 3(e) while the voltage of the coil 4 being indicated by a broken line in FIG. 3(e), wherein each voltage of said coils 3 and 4 are respectively retarded by an angle of about 120 with respect to each voltage of said coils l and 2.

The operation of the first embodiment constructed as described above will now be explained. The operation of the various parts of the embodiment which take place along with the rotation of the engine will be explained with reference to FIG. 3. When the generated voltage of the capacitor charging coil 1 begins to increase in the positive direction at a time T1 in FIG. 3, the capacitor 13 is charged with the voltage generated at the capacitor charging coil 1 flowing through a circuit comprising the coil 1, the diode 12, the capacitor 13 and a parallel circuit consisting of the diode 14 and the primary winding 15a of the ignition coil 15. Although at a time T2 a positive voltage is generated at the capacitor charging coil 2, the number of turns of the coil 2 is too small to charge the capacitor 13 at low speed rotation of the engine. Consequently, the capacitor 13 is finally charged to develop thereacross the terminal voltage as indicated by a solid line in FIG. 3(e). At a time T3 when the generated voltage of the coil 1 changes from the positive to the negative direction, the voltage generated at the coil 1 is shortcircuited through the circuit comprising the part lb of the coil 1 and the diode 18 and the circuit comprising the other part 1a of the coil 1, the primary winding a of the transformer 20, the diode 19 and the part lb of the coil 1. At this stage, an output voltage is produced at the secondary winding 20b as indicated by a solid line in FIG. 3(d) and the thyristor 17 is made conductive at a time T4 in FIG. 3, thereby to discharge the charge stored in the capacitor 13 through the circuit comprising the thyristor 17 and the primary winding 15a of the ignition coil 15 and to induce a high voltage at the secondary winding 15b of the ignition coil 15, thus sparking at the spark plugs 16. Here, the purpose of the diode 14 is to keep the current flowing though the primary winding 15a of the ignition coil 15 to extend the arc duration of the ignition spark. The above-mentioned operation is repeated twice for every rotation of the engine crankshaft, namely two ignition sparks are caused for each revolution of the magneto generator. In the daytime, the switch means 27a and 27b are opened, and thereby the battery 25 is charged with the half wave voltage of the positive direction generated at the coils 3 and 4, whose waveforms are shown in FIG. 3(e) through the diodes 23 and 24, while in the nighttime, the switch means 27a and 27b are closed so that the lamp loads 28 are mainly supplied with the electric current from the full-wave rectifier 26.

Next the operation of the above-mentioned system will be explained when the engine is rotated in the reverse direction by accident. The generated voltages shown in FIG. 3 are changed in the opposite directions. During the very low speed operation of the engine, at a time T1 the capacitor 13 may be charged with the voltage generated at the coil 2 since the positive output voltage of the transformer 20 exists too short to make the thyristor 17 conductive, as indicated by a broken line in FIG. 3(d). And at a time T2 the charge stored in the capacitor 13 is discharged by the output signal of the transformer 20, thereby to cause ignition sparks at the spark plugs 16. However, during the low and high speed rotation of the engine, the duration of the positive output voltage of the transformer, as indicated by the one-dot-chain line in FIG. 3(d), becomes enough longer to make the thyristor 17 conductive, whereby the voltages produced at the coils l and 2 are bypassed through the thyristor 17 not to charge the capacitor 13. Therefore the engine is prevented from rotating in the reverse direction.

In the first embodiment as described above, the pole cores 7 and 11 on which the capacitor charging coil 2 and the battery charging coils 3 and 4 are respectively wound are positioned at the both adjacent sides of the pole core 6 on which the capacitor charging coil 1 is wound, as shown in FIG. 2. However, during the normal running of the engine, as the generated voltages of the coils 3 and 4 are cut by the diodes 23 and 24 when the thyristor 17 becomes conductive as shown in FIG. 3,.the-on-off operation of the switch means 27b has no influence on the generated voltage of the coil 1, whereby the fluctuation of the ignition timing due to the on-off operation of the switch means 27b is prevented.

Further in the first embodiment as described before, the generated voltage of the coil 2 may be fluctuated a-little due to on-off operation of the switch means 27b, thereby causing fluctuation of the charging voltage of the capacitor 13 since the coils 2 and 3 are wound on the same pole core 7. To prevent the fluctuation of the charging voltage on the capacitor 13, only the capacitor charging coil 2 is to be wound on the pole core 7 without the battery charging coil 3 and the output voltage of the coil 4 is to be supplied to the battery 25 through the full-wave rectifier 26.

FIG. 4 shows the second embodiment of the present invention, in which the capacitor charging coil 1 is connected in series with the capacitor charging coil 2 whose generating voltage is retarded by the angle of 60 with respect to that of the coil 1 and the diodes l2 and 19 are respectively connected in parallel with the capacitor charging coils 2 and l. The operation of the 

1. A capacitor discharge type contactless ignition system for an internal combustion engine comprising; a first capacitor charging coil mounted in a magneto generator driven by an engine and for generating a first alternating current in accordance with the rotation of said magneto generator; a second capacitor charging coil mounted in said magneto generator and for generating a second alternating current in accordance with the rotation of said magneto generator whose phase is retarded by a certain angle from that of said first alternating current, whereby when the engine rotates in an undesired direction the second positive half wave of said second alternating current being generated prior to the first positive half wave or said first alternating current and the latter certain part of said second positive half wave overlapping the former certain part of said first positive half wave; a capacitor means forming a capacitor charging circuit connected in series with said first and second capacitor charging coils and including rectifying means for rectifying said first and second alternating current and applying the rectified current to said capacitor; means forming a capacitor discharging circuit including said capacitor, a semi-conductor switching element having a control gate and a primary winding of an ignition coil having a primary and secondary winding; a spark plug connected with said secondary winding of said ignition coil; and a pulse generator connected with said control gate and for generating an ignition pulse in Synchronism with the rotation of said magneto generator during the rotation of the engine in a desired direction, whereby the charge stored in said capacitor is discharged through said capacitor discharging circuit, to thereby induce a high voltage at said secondary winding to produce an ignition spark at said spark plug; said pulse generator generating a reverse protecting pulse during the rotation of the engine in an undesired direction in order to make said semi-conductor switching element conductive for each period while said second positive half wave is generated, whereby said second positive half wave is shortcircuited around said capacitor and said first positive half wave is sequentially short-circuited through said semiconductor switching element due to the overlap of said first and second positive half wave, thus preventing said spark plug from producing an ignition spark which may otherwise keep the rotation of the engine in the undesired direction.
 2. A capacitor discharge type contactless ignition system as defined in claim 1 wherein said pulse generator is a transformer whose primary winding is connected across said first capacitor charging coil and whose secondary winding is connected with said control gate whereby said ingition pulse and reverse protecting pulse are generated when the negative half wave is generated at said first capacitor charging coil.
 3. A capacitor dishcarge type contactless ignition system as defined in claim 1 wherein said first and second capacitor charging coil are connected in series with each other.
 4. A capacitor discharge type contactless ignition system as defined in claim 1 wherein said first and second capacitor charging coil are connected in parallel with said capacitor.
 5. A capacitor discharge type contactless ignition system as defined in claim 1 wherein said pulse generator includes; a first transformer whose primary winding is connected across said first capacitor charging coil and whose secondary winding is connected with said control gate of said semi-conductor switching element whereby said ignition pulse is generated when the negative half wave is generated at said first capacitor charging coil; and a second tranformer whose primary winding is in series connected with said second capacitor charging coil and whose secondary winding is connected with said control gate of said semi-conductor switching element, whereby said reverse protecting pulse is generated at said secondary winding of said second transformer during the rotation of the engine in the undesired direction whenever the positive half wave is generated at said second capacitor charging coil.
 6. A capacitor discharge type contactless ignition system as defined in claim 1 wherein said pulse generator includes a transformer having a primary and secondary winding, the one part of said primary winding being in series connected with said second capacitor charging coil, the other part of said primary winding being connected across said second capacitor charging coil, and said secondary winding being connected with said control gate of said semi-conductor switching element whereby said ignition pulse is generated at said secondary winding during the rotation of the engine in the desired direction whenever the negative half wave is generated at said second capacitor charging coil and said reverse protecting pulse is generated at said secondary winding during the rotation of the engine in the undesired direction whenever the positive half wave is generated at said second capacitor charging coil. 